Abstract: The effects of different concentrations of carboxymethyl chitosan on rice nitrogen metabolism,grain and brown rice protein contents and grain protein yield were studied.The results showed that applying carboxymethyl chitosan could strongly improve the abilities of transportation of N in functional leaves and stem-sheaths of rice and key enzyme activities of nitrogen metabolism and contents of total N and protein N in brown of rice comparing to CK.Applying 0.5% concentration of carboxymethyl chitosan resulted in the highest rice grain protein and which was 19.8% higher comparing to CK.Therefore,0.5% carboxymethyl chitosan was recommended for rice production.